Disease Pathogenesis and Modification for CaV1.1-Associated Hypokalemic Periodic

CaV1.1 相关低钾血症周期性疾病的发病机制和修饰

基本信息

批准号：
8496723
负责人：
STEPHEN C. CANNON
金额：
$ 35.79万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-07-01 至 2017-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8496723
关键词：
Animal Model Arginine Biological Models Biopsy Calcium Channel Carbohydrates Cations Charge Coupling Data Defect Dependence Disease Environment Exercise Extravasation Failure Familial Periodic Paralysis Family Fiber Gene Targeting Genetically Engineered Mouse Glucose Goals Hour Human Hypokalemia Hypokalemic periodic paralysis In Vitro Inborn Genetic Diseases Ingestion Insulin Intervention Ion Channel Ion Pumps Link Missense Mutation Modeling Modification Molecular Movement Mus Muscle Muscle Fibers Mutate Mutation Oocytes Paralysed Pathogenesis Pathologic Phenotype Predisposition Proteins Rare Diseases Recurrence Reporting SCN1A protein Scientific Advances and Accomplishments Serum Skeletal Muscle Sodium Channel Source Stress Testing Therapeutic Therapeutic Intervention Tissues Treatment Efficacy Work base burden of illness density efficacy testing in vivo kindred mouse model mutant mutant mouse model response sensor simulation tool voltage voltage clamp

项目摘要

DESCRIPTION (provided by applicant): Hypokalemic periodic paralysis (HypoPP) is a dominantly inherited disorder of skeletal muscle in which recurrent attacks of weakness are caused by intermittent failure of fiber electrical excitability. Episodes occur in association with hypokalemia (K+ < 3 mM) and may be triggered by carbohydrate ingestion, exercise, or stress. The molecular defect in HypoPP is heterogeneous, with 60% of families having missense mutations in CACNA1S encoding the L-type Ca channel CaV1.1, another 20% have missense mutations in SCN4A encoding the voltage-gated Na channel NaV1.4, and the remainder undetermined. Despite this scientific advance, the pathogenic basis for the transient attacks of fiber depolarization with loss of excitability is not fully established. Curiously, all 8 mutationsin NaV1.4 and 6 of 7 in CaV1.1 occur at arginine residues in S4 voltage-sensor domains. Thus far, all 6 NaV1.4-HypoPP mutations studied in the cut-open oocyte have revealed a small anomalous cation current activated at hyperpolarized potentials, via conduction through a "gating pore" between the mutated S4 segment and the channel protein. We recently reported a gating pore current in muscle fibers from NaV1.4-R669H mice. This gating pore conductance is hypothesized to be the source of the inward current that triggers the paradoxical depolarization of HypoPP fibers in low K+. A major unanswered question is whether the homologous R/X mutations in CaV1.1 associated with HypoPP also produce a gating pore current, thereby providing supportive evidence for a common pathomechanism for HypoPP arising from mutations in NaV1.1 or CaV1.1. The overall goal of this project is to gain a greater understanding for the pathologic basis of HypoPP resulting from CaV1.1 mutations. We have used a gene-targeting approach to generate an R528H knockin mutation of CaV1.1 as a model for HypoPP. The Aims of this project are: (1) to extend the phenotypic characterization of the CaV1.1-R528H mouse for features of hypokalemic periodic paralysis, (2) to test the hypothesis that the CaV1.1-R528H channel conducts an anomalous gating pore current (3) to characterize the integrity of Ca2+- release in CaV1.1-R528H muscle fibers, (4) to explore potential disease-modifying agents in the mouse model of CaV1.1-HypoPP. This work will extend our understanding of the pathogenesis for attacks of weakness in HypoPP and will provide a model system to test the efficacy of therapeutic strategies, both as a means to reduce or ameliorate the burden of disease and to provide confirmatory experimental support for the proposed mechanism of disease.

描述（由申请人提供）：低钾血症周期性瘫痪（HYPOPP）是骨骼肌的主要遗传疾病，其中纤维电兴奋性的间歇性失败引起了反复发作的无力攻击。情节发生与低钾血症（K+ <3 mm），可能是由碳水化合物摄入，运动或压力引起的。 HYPOPP中的分子缺陷是异质的，有60％的家族在编码L型Ca通道CAV1.1中具有错义突变，另外20％的家庭在编码电压门控的Na通道NAV1.4的SCN4A中具有错义突变，以及其余的未确定。尽管有科学的进步，但尚未完全确定纤维去极化瞬时攻击的致病基础。奇怪的是，在S4电压传感器结构域中的精氨酸残基中，在cav1.1中的7个NAV1.4和6中的所有8个突变。到目前为止，在切开的卵母细胞中研究的所有6种NAV1.4-HYPOPP突变都揭示了通过突变的S4片段和通道蛋白之间的“门控孔”传导在超极化电位处激活的小型异常阳离子电流。我们最近报道了NAV1.4-R669H小鼠的肌肉纤维中的门控孔电流。假设这种门控孔电导是触发低K+中HypOPP纤维的矛盾去极化的内向电流的来源。一个主要的未解决的问题是，与HypOPP相关的CAV1.1中的同源R/X突变是否也产生了门控孔电流，从而为NAV1.1或CAV1.1突变引起的HypOPP具有共同的病理性提供支持证据。该项目的总体目标是对CAV1.1突变引起的HYPOPP的病理基础有更深入的了解。我们已经使用了一种基因靶向方法来生成CAV1.1的R528H敲蛋白突变作为HYPOPP的模型。该项目的目的是：（1）扩展CAV1.1.1.1-R528H鼠标的表型表征在降压性周期性麻痹的特征中，（2）测试CAV1.1.1.1-R528H通道的假设，即CAV1.1.1-R528H通道会导致ca2+-1-r528的范围fib的范围，以表征异常的门孔（3） CAV1.1-HYPOPP小鼠模型中的疾病改良剂。这项工作将扩展我们对HYPOPP无力发作的发病机理的理解，并将提供一个模型系统来测试治疗策略的功效，这是减少或改善疾病负担的手段，并为拟议的疾病机制提供确认的实验性支持。